berniebeaudry Posted September 5, 2013 Report Share Posted September 5, 2013 I'm doing the troubleshooting from afar so I have limited info just yet. Shooting on an HPX 170 with an Atomos Samuri video recorder (records on a hard drive). Using a regulated IDX V mount battery plate that is powering the camera, the recorder, and the receiver for the camera hop. There is regular clicking (approximately 1 second intervals) that is audible in the camera. If the hop is powered internally with its own batteries the click goes away. This has happened with two different hop receivers (we hire local audio and this is a different operator and a different city and a different receiver set up). Obviously there's a ground loop somewhere and I'll tell them how to isolate it better when they call back, but what to do to solve it? I made up a new two pair xlr for the system and double checked it before they hit the road but not with all the components plugged together. The camera hop is important because they need the mobility and a solid record to camera because of short turnaround before the show airs. There is a back up recording but would like to get this working right. Lifting the ground on one end of the xlrs is the first thing that comes to mind to break the loop. Any other ideas? Quote Link to comment Share on other sites More sharing options...
studiomprd Posted September 5, 2013 Report Share Posted September 5, 2013 " regular clicking ... that is audible in the camera. " physically audible?? in the headphones audible ?? in the recording audible ?? even in the RX output audible ?? based on your troubleshooting description there is an issue in the camera or recorder/drive (they have not changed..?) or maybe even the IDX plate... further "trial and error" ?? sounds like internal RX powering is the workaround... Quote Link to comment Share on other sites More sharing options...
berniebeaudry Posted September 5, 2013 Author Report Share Posted September 5, 2013 " regular clicking ... that is audible in the camera. " physically audible?? in the headphones audible ?? in the recording audible ?? even in the RX output audible ?? based on your troubleshooting description there is an issue in the camera or recorder/drive (they have not changed..?) or maybe even the IDX plate... further "trial and error" ?? sounds like internal RX powering is the workaround... Just got more info and the immediate work around is internal powering. I'm told its a noise pulse that occurs at regular intervals and is being recorded. I told him to determine if its on one channel or both. Different xlrs were used last week so I don't think its the xlrs. I also suggested taking the recorder out of the equation to see if that makes the issue go away. The camera blew up today (long story) so it could have been a camera issue. They'll try the configuration with the replacement camera and see if anything changes. I've also told him to contact the vendor for the batteries (B4B) and pick their brain. I'll also see if the noise is coming out of the rx without being connected to the camera. Thanks Mike. Quote Link to comment Share on other sites More sharing options...
roshambomedia Posted September 5, 2013 Report Share Posted September 5, 2013 Sounds like something isn't shielded inside one of those boxes, i.e. ground wire. Have you tried a "divide and conquer" approach? Kind of an engineering thing. Just break the signal into pieces and find out where things aren't happy in pairs, and then start adding the chain back together. Here's a good document on ground-loops(below). Is there a hacker space near you? I know nullspace labs in LA has a lot of people there that know about electronics... might be able to help you. http://www.jensen-transformers.com/an/generic%20seminar.pdf This is like the very basics of electrical noise and ground loops. Quote Link to comment Share on other sites More sharing options...
studiomprd Posted September 5, 2013 Report Share Posted September 5, 2013 this is nothing new, as there are many devices that can cross pollute other devices, and one typical path is through the powering interconnections. Quote Link to comment Share on other sites More sharing options...
roshambomedia Posted September 5, 2013 Report Share Posted September 5, 2013 Just got more info and the immediate work around is internal powering. I'm told its a noise pulse that occurs at regular intervals and is being recorded. I told him to determine if its on one channel or both. Different xlrs were used last week so I don't think its the xlrs. I also suggested taking the recorder out of the equation to see if that makes the issue go away. The camera blew up today (long story) so it could have been a camera issue. They'll try the configuration with the replacement camera and see if anything changes. I've also told him to contact the vendor for the batteries (B4B) and pick their brain. I'll also see if the noise is coming out of the rx without being connected to the camera. Thanks Mike. Ha, lol... well that sounds like the impedance spiked, which could happen if some wires were exposed. Hopefully your problem is solved. Quote Link to comment Share on other sites More sharing options...
studiomprd Posted September 5, 2013 Report Share Posted September 5, 2013 " sounds like the impedance spiked, which could happen if some wires were exposed. " Quote Link to comment Share on other sites More sharing options...
roshambomedia Posted September 5, 2013 Report Share Posted September 5, 2013 FYI, there is this place: http://www.tcmaker.org/blog/ In the future, if you need community support for electronics, these places are really good. I regularly contribute to building hardware, programming, and doing cinema hacks. Might be worth your effort to check it out. Quote Link to comment Share on other sites More sharing options...
roshambomedia Posted September 5, 2013 Report Share Posted September 5, 2013 " sounds like the impedance spiked, which could happen if some wires were exposed. " While were on that subject... have either of you seen the home brew power kits for the Black Magic camera... just some radioshack power connectors, wired into the cheap chinese usb power-bricks? It sketches me out. I've hooked those up to a scope and they don't exactly have consistent power output, but it works fine... Quote Link to comment Share on other sites More sharing options...
studiomprd Posted September 5, 2013 Report Share Posted September 5, 2013 " It sketches me out. " Quote Link to comment Share on other sites More sharing options...
berniebeaudry Posted September 5, 2013 Author Report Share Posted September 5, 2013 Ha, lol... well that sounds like the impedance spiked, which could happen if some wires were exposed. Hopefully your problem is solved. No wires exposed. Camera person plugged into the unregulated jack on the battery and put too much voltage into the camera. Yikes! Thanks for the links but neither one worked. Quote Link to comment Share on other sites More sharing options...
berniebeaudry Posted September 5, 2013 Author Report Share Posted September 5, 2013 Sounds like something isn't shielded inside one of those boxes, i.e. ground wire. Have you tried a "divide and conquer" approach? Kind of an engineering thing. Just break the signal into pieces and find out where things aren't happy in pairs, and then start adding the chain back together. Here's a good document on ground-loops(below). Is there a hacker space near you? I know nullspace labs in LA has a lot of people there that know about electronics... might be able to help you. http://www.jensen-transformers.com/an/generic%20seminar.pdf This is like the very basics of electrical noise and ground loops. Just spoke on the phone with them and told them the sequence to isolate the problem. We'll see what they come up with. Quote Link to comment Share on other sites More sharing options...
ben lowry Posted September 5, 2013 Report Share Posted September 5, 2013 Try lifting pin 1 in the hop-to-cam XLRs? ben lowry Quote Link to comment Share on other sites More sharing options...
berniebeaudry Posted September 5, 2013 Author Report Share Posted September 5, 2013 Try lifting pin 1 in the hop-to-cam XLRs? ben lowry going to give that a try after we determine what component is unhappy. Quote Link to comment Share on other sites More sharing options...
LarryF Posted September 5, 2013 Report Share Posted September 5, 2013 going to give that a try after we determine what component is unhappy. Were you running line level out from the receivers? Best, Larry F Lectro Quote Link to comment Share on other sites More sharing options...
berniebeaudry Posted September 5, 2013 Author Report Share Posted September 5, 2013 Were you running line level out from the receivers? Best, Larry F Lectro First rx was an Srb and I think so. The one today is Zaxcom and again I think so. Will confirm that. Quote Link to comment Share on other sites More sharing options...
berniebeaudry Posted September 5, 2013 Author Report Share Posted September 5, 2013 The IDX plate has a regulator circuit in it to drop the voltage down to the 7.4 volts required by the camera from the 14.8 volts of the V mount battery. Could a bad regulator generate a pulse like that? Quote Link to comment Share on other sites More sharing options...
LarryF Posted September 5, 2013 Report Share Posted September 5, 2013 The IDX plate has a regulator circuit in it to drop the voltage down to the 7.4 volts required by the camera from the 14.8 volts of the V mount battery. Could a bad regulator generate a pulse like that? We've never run into to that. Typically they will oscillate at high frequencies rather than pulse once a second. They usually fail open (no current flow) or short out. If you were running line levels then that was a strong pulse. Some regulators will shutdown when they overheat to protect themselves, cool off and come back on and this can happen at a rate from several seconds to hundreds of times per second. Best, Larry F Lectro Quote Link to comment Share on other sites More sharing options...
berniebeaudry Posted September 5, 2013 Author Report Share Posted September 5, 2013 The SRb was running at line level. Quote Link to comment Share on other sites More sharing options...
Michael McQueen Posted September 6, 2013 Report Share Posted September 6, 2013 so i was the first person to encounter this issue that bernie is referring to. i was shown their rig before our first shoot via cell phone pics. pictured was a power tap splitter. i had a power tap to lectro style connector, easy enough. well when we setup and i plugged in, we had that clicking going on. i unplugged power from srb and it went away. so my next instinct was to power the srb with my sony style battery, stuck that on, sound was fine, so we went to work. producer had concerns for future sound mixers working with same gear. and after further inspection, appeared that my "lectro style" connector was actually a few mm's too short, but yet still powered the srb. so i figured the clicking came from possibly a ground loop issue caused but that short connector. i know my ta3-xlr cables are good, i use them regularly (today again actually) and they are fine. and actually Mr. Toline made them, so until he's dead, they have a lifetime guarantee. some more specs: the click came through camera and external recorder. i also tried running p-tap into a different port on breakout splitter and the additional power tap on the battery mount, still had clicks. unfortunately we were kind of in a rush so i just went to battery mode. it worked, so we went on making kick ass tee-vee. i wish i would have had more supplies with me to test further this scenario and i hate that another location mixer is having to deal with this. but i have a good feeling it has something to do with the v-mount's setup, how to fix it tho, i am not certain. but we'll keep at it and figure it out, trouble shooting is our job. Quote Link to comment Share on other sites More sharing options...
berniebeaudry Posted September 6, 2013 Author Report Share Posted September 6, 2013 Thanks Michael, There isn't a lot of time on this gig to deal with such things. I appreciate your pushing thru and having a work around available. Indeed you did make some kick ass tv! What a start to the season! Hopefully they're trouble shooting this as we speak and we can at least find out which box isn't happy. Quote Link to comment Share on other sites More sharing options...
ProSound Posted September 6, 2013 Report Share Posted September 6, 2013 I always power my SRB externally I encourage everyone else to as well. Power on a full size camera is always clean and problem free but on these smaller format rigs it seems to have issues. Quote Link to comment Share on other sites More sharing options...
berniebeaudry Posted September 6, 2013 Author Report Share Posted September 6, 2013 I always power my SRB externally I encourage everyone else to as well. Power on a full size camera is always clean and problem free but on these smaller format rigs it seems to have issues. Thanks Whitney, We may have to take that approach if we can't solve this. It'll be the same camera for the whole season so we have that going for us. We were going for a more streamlined rig with the external recorder/monitor, the V mount full size battery and multi-tap battery mount. Its too bad this is an issue. Today the rx is a Zaxcom so the problem is indeed being caused by external powering not a particular brand or model of rx. Quote Link to comment Share on other sites More sharing options...
Marc Wielage Posted September 6, 2013 Report Share Posted September 6, 2013 I always power my SRB externally I encourage everyone else to as well. Power on a full size camera is always clean and problem free but on these smaller format rigs it seems to have issues. That's my advice as well. Quote Link to comment Share on other sites More sharing options...
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